So...now I know what they mean by chicken math ... and a question

I figured I need a few more hens, and since straight run means boys too... I figured i needed just a few more than a few chicks

Last night my husband and I got 11 new babies from the neatest little poultry farmer with the cutest kids ever!

We put them in our current coop bulding. They are near my older chicks(9-10 weeks) We built a brooder with heat light, etc. for them, sectioning off a part of the shed that is adjacent to the roost area of the older chicks, but seperated by wire. We closed off the side where the wire is with a board (so they are blocked from the big chicks completely) with plans to open it up when they are bigger so they can get to know each other without being able to get too close. My question is... how long should they be kept closed off, and then how long before the can run with the bigger gals?...and since we are starting chicks again, is it ok to keep my bigger ones on the chick food instead of having two types... Or should they get graower food now? thanks!